The search masks used to define search panels have three sections:
- Search controls
- Display columns
All three use managed properties as their source.
Managed properties should be defined at the Webapp or Office 365 tenant level as searchable, queryable, retrievable, and (refinable if needed)
Managed properties for Controls
Managed properties for controls should return results correctly when used in a Search Centre (or in the search box on a site) with the KQL syntax “managedproperty:text”.
“Type” is not so important provided they return results correctly.
The exception here is date columns which must be of type date and mapped to the appropriate date crawled property (RefinableDateSingle) control to use the Date picker control.
In SharePoint Online it is not possible to define the Type of your own managed property. Instead, SharePoint makes a range of predefined "Refineable" managed properties available, eg RefineableDateSingle00 to RefineableDateSingle04 which you can give an "Alias" to, and map to the desired managed property. The "Refineable" properties include string, etc
Managed properties for Result Display and Refining
The display and refineable columns need to be user friendly. A mapping to the simple crawled property ows_column will usually suffice. This prevents more complex columns like user, managed metadata, or content type, etc, from displaying a lot of unnecessary and confusing text